V0BtaTrack list

V0BtaTrack list is a list of BtaCandidate objects that combines Ks, Lambda, and gamma conversions that are identified as such by the TrkV0Selector module in the TrkFixup package. This page describes the selection of these particles. See BAD 1628 for other aspects of TrkFixup.

Variable Cut Value

Ks

Lambda

Gamma Conversions

Invariant mass of the track pair [pdg-0.007 GeV, pdg+0.007 GeV] [0, 0.03 GeV]
Distance between the V0 vertex and the primary vertex [0.5 cm, 80 cm] [1.5 cm, 80 cm]
Distance of closest approach of the track pair < 0.75 cm
Vertex probability of the track pair > 0.02
Primary pointing (dot-product of the V0 flight direction with the normalized displacement vector from the primary vertex) > 0.998
Number of DCH hits before the V0 vertex <= 2
Use of detector PID information n/a see below

In addition, the detector-level PID information is used to further discriminate the Lambda and the gamma conversions. This combines the knowledge from the DRC, DCH, and SVT detectors.


Page Maintainer: Tomohiko Tanabe
Last Updated: 11/20/2007